Over the last two months, besides being completely buried with the "day job", I have become enamored of the SBC2440.
Seriously. For reasonable cost here is what you get:
arm290t processor running at 400MHZ
64MB memory + 64MB flash
Runs linux 2.6 kernel with all drivers
Built in audio
lots of GPIO
SD/MMC card socket with driver (supports 1GB)
This completely eliminates any need to hack on the CPU board of the pinball machine. It allows the use real tools, removes all memory constraints (ok, not all, but compared to the prop chip...) removes the need for fabricating an audio setup and fits the criteria I set out for:
all hardware and software needs to be available such that if I want to build another machine just like this one I can. This means that using a PC "found laying around" will not do.
all of the hardware needs to fit in the standard pinball form factor.
In short, this board could easily replace the entire existing the CPU board. There is still need of some additional hardware fidgeting, but using this SBC will allow a lot more progress on things I want to work on.
Now I just need to come up with a little spending cash for XTCPinball. That and dust things off around here.